the minimal Ruby equivalent would be

    ruby -run -ehttpd .

Here's a handy snippet for bashrc:

    function S {
      ruby -run -ehttpd . -p${1-8080}  # default to port 8080 unless given as parameter
    }

although that server is very horrible

Works fine for some tests, but it's single threaded. If you need concurrency:

    twistd -no web --path=.

Perhaps, but the use case it usually finds is "I need a webserver, here. Now."

Python is nearly always installed, and that depends on nothing but the standard library. You can stick an alias in your dotfiles (I have, it's called "serve-this") and not have to worry about having twisted¹ getting to wherever your dotfiles get put. (I distribute my dotfiles over git/github, so it's really easy to move them around. More work to get Twisted.)

¹Or Ruby… or Go…

Twisted is pre-installed on OS X and various Linux distributions...

or in go:

    package main

    import (
        "flag"
        "net/http"
    )

    var serveDir = flag.String("d", ".", "Directory to serve from")

    func main() {
        flag.Parse()
        panic(http.ListenAndServe("127.0.0.1:8000", http.FileServer(
            http.Dir(*serveDir))))
    }

What's wrong with it? Honestly, I don't know. I know Python probably isn't a great choice for performance reasons, but anything else? It's super easy to build off and configure. Seems fine for a beginner (which I admittedly am; hence my asking).

Main issue is it's single threaded. So if you use it to share big files with an other machines, only 1 file can be downloaded at a time and a download will block browsing of available files.

It's also very buggy. Its only excuse is being old.